Drum assembly for washing and drying machines and method for making it

ABSTRACT

The present invention relates to an improved drum assembly for washing and drying machines, in which the section of the wedge elements ( 8 ) facing the drum ring ( 3 ) and provided for engaging with the latter is formed, before the drum assembling, with an edge ( 9 ) defined by an inwardly turned wall of the wedge element and parallel to the surface of the front ring ( 3 ). This front ring is in turn provided, at each wedge element ( 8 ) with a window ( 10 ) the contour of which is so deformed as to provide a deformed portion ( 11 ) adapted for firmly engaging the edge ( 9 ). The invention provides a direct mechanical coupling between the wedge elements and front ring element, i.e. a mechanical coupling which does not comprise any welding spots susceptible to favor oxidation and sealing failure problems of the made connection.

BACKGROUND OF THE INVENTION

The present invention relates to an improved drum assembly for washing,drying machines, and the like, as well as a method for making said drumassembly.

The drum assemblies of the type concerned by the present inventionconventionally comprise a body of substantially drum configuration. Thisdrum body is formed by a perforated metal band constituting thecylindric wall of the drum body, by a rear closure disc for closing thedrum body, which supports the cross member supporting the shaft of thedrum, and a front ring element defining the front loading mouththerethrough the cloth articles to be processed are loaded into thedrum. In the case of a top loading, on the other hand, the front ringelement is replaced by a closing cover, whereas the side band isprovided with an opening for introducing the cloth articles into thedrum.

In order to provide an efficient tumbling of the cloth articles to bewashed or dried, on the inside surface of the perforated metal bandforming the cylindric wall of the drum are provided a plurality ofprojections, having a substantially wedge-like cross section, whichoperate as “entrainment” elements. Actually, owing to the provision ofthese projections, the rotary movement applied to the drum assembly willcause the linen loaded therein to be upwardly entrained and fall bygravity, thereby aiding the washing operation.

The provision of the above mentioned projections, which will behereinafter called “wedge elements”, causes, however, problems ordifficulties in properly coupling the metal band and ring element orfront cover. Because of the provision of the mentioned wedge elements,in fact, the edge or rim of the mentioned metal band will have an unevencontour, which, on the other hand, must be perfectly fitted or matedwith the contour of the ring element or front cover of the drum.

Prior solutions for providing such a connection include the use of spotwelding operations between the respective walls of the ring or frontcover element and the drum wedge elements, formed on the correspondingsurface engagement portions. Such a spot welding method, however, couldalter or modify the required chemical-physical properties of the drummaterial (chromium stainless steel, AISI 430), which is would beseriously affected by a thermal treatment like that deriving from a spotwelding operation. On the other hand, this spot welding operation, whichmust involve a number as low as possible of regions of the drum, doesnot provide a connection having the desired strength and duration. Infact, the welding spots do not provide a structurally continuousconnection and, moreover, as stated, could undesirably modify the drummaterial thereby favoring oxidation phenomena which would be verydangerous for the time stability of the performed connection.

In addition to the above mentioned drawbacks, to weld the front ringelement or cover on the wedge elements of the drum is disadvantageoussince it does not allow a proper centering of these elements. Actually,as the welding operation is performed, the ring or cover element can bedisplaced from a proper position centered with respect to the cylindricband on which they must be locked, thereby the end product may beaffected by openings or undesired gaps between the connected portions.

To the foregoing it should be added that for welding the drum,additional welding materials and power are required, thereby increasingthe end cost of the drim assembly.

SUMMARY OF THE INVENTION

Accordingly, the aim of the present invention is to provide such a drumassembly for washing, drying and the like machines which has amechanical strength greater than that of commercially available likedevices, mainly at the level of the mutual connection regions couplingthe mentioned wedge elements and front ring or cover element.

Within the scope of the above mentioned aim, a main object of thepresent invention is to provide a drum assembly of the above mentionedtype which is effectively devoid of any unevenness like those whichoccur in the connection regions of the wedge elements and the front ringor cover element in prior drum assemblies.

Yet another object of the present invention is to provide a method formaking the above mentioned drum assembly, which is specifically designedfor reducing to a minimum the end cost of washing, drying and the likemachine drum assemblies.

According to one aspect of the present invention, the above mentionedaim and objects are achieved by an improved drum assembly for washing,drying and the like machines, of the type including a cylindric bandprovided with a plurality of wedge elements facing the inside of thedrum assembly, a closing rear disc and a front ring element,characterized in that said drum assembly comprises connecting means fordirectly mechanically connecting said ring element and band, at saidwedge elements of said band.

According to further features of the inventive drum assembly, saidconnecting means comprise projecting or raised walls provided on thatsection of each said wedge element engaging said ring element, saidprojection portions being adapted to cooperate with correspondingprojecting or raised portions of said ring element. Said projectingportions, in particular, comprise a wall formed on the end of the wedgeelements facing the ring element and directed inwardly of said wedgeelements, at a position substantially parallel to the surface of thering element therewith said wall must be connected. In turn, saidprojecting portions of said ring element comprise a deformed or upsetedge or rim portion provided at the connection section on each wedgeelement and having such a size and shape to be housed inside each saidwedge element, above and beyond the mentioned projecting wall.

According to further features of the drum assembly according to thepresent invention, said deformed edge or rim portion comprises a wallfacing the inside of the drum assembly. After having performed themechanical connection, the mentioned deformed edge or rim portion willbe rearwardly turned and upset against said wall of the respective wedgeelement.

According to a modified embodiment of the drum assembly of theinvention, said direct connection mechanical means comprise a portion ofsaid wedge elements axially projecting on the outside of said cylindricband, for cooperating with a corresponding window of the front ringelement, to be locked inside the latter, at the contour thereof.

The method for making the above disclosed drum assembly, which alsoconstitutes a main aspect of the present invention, is essentiallycharacterized in that it comprises the step of cold anchoring said frontring or cover element and cylindric band, at the wedge elements of saidband. The method is moreover characterized in that said anchoring orconnecting step is performed by an upsetting operation which is precededby a self-centered connection between said front ring or cover elementand said cylindric band of the drum assembly.

Further features of the inventive method are clearly defined in theremaining dependent claims.

With respect to prior drum assemblies, the inventive drum assemblyprovides the advantage of allowing a mechanical direct connection of thewedge elements and front ring or cover element, i.e. a connection whichdoes not comprise any welding spots favouring oxidation and sealingfailure phenomena of the performed connection.

The mechanical sealing properties of the subject connection are moreovermuch more stable and efficient, than prior welding spot connections,since the subject connection is extended to the overall mutual couplingsection of the wedge elements and corresponding portion of the frontring or cover element, and not to only a portion thereof, as in a spotwelded connection.

The cold connection performed by upsetting a projecting portion of saidfront ring or cover element on the contour of a corresponding wedgeelement, furthermore, provides a self-centering effect. Thus, the drumassembling operation can be carried out a fully automatic manner due tothe mutual engagement of the portions being connected, thereby providinga well finished final product.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and yet other objects and advantages will becomemore apparent hereinafter from the following disclosure of a preferredembodiment of the drum assembly according to the present invention whichis illustrated, by way of an exemplary but not limitative example, inthe figures of the accompanying drawings, where:

FIG. 1 is a general perspective view illustrating the drum assemblyaccording to the present invention;

FIG. 2 is a partial cross-sectional view illustrating the drum assemblyshown in FIG. 1;

FIG. 3 illustrates the drum assembly shown in FIG. 1 during apreassembling operation in which the front ring element is preassembledon a perforated cylindric band;

FIG. 4 illustrates a detail of the cross-section of a wedge elementprovided on the drum assembly of FIG. 3;

FIG. 5 illustrates a detail of a window provided through the ringelement of FIG. 3;

FIG. 6 illustrates the detail A of FIG. 2, in a ring elementpreassembling condition;

FIG. 7 is a top plan view illustrating the detail of FIG. 6;

FIG. 8 illustrates the detail A of FIG. 2, at the end of the ringelement assembling operation;

FIG. 9 is a top plan view illustrating the detail of FIG. 8; and

FIGS. 10 and 11 illustrate a modified embodiment of the drum assemblyrespectively shown in FIGS. 3 and 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drum assembly according to the invention has been generallyindicated by the reference number 1 in FIG. 1 and is of a type suitablefor application to washing, drying or the like machines. In thisconnection it should be pointed out that through the herein illustratedand shown example refers to a front loading type of drum assembly, theinvention, also covers the so-called top loading drums. In the lattercase, the front ring element will be replaced by a closing cover elementand the perforated cylindric band will be provided with a mouth forallowing the linen to be washed and/or dried to be introduced into thedrum.

The drum assembly 1 of FIG. 1, fully made of a stainless steel material(preferably chromium stainless steel AISI 430) comprises:

a metal perforated band 2, forming the side cylindric wall of the drumassembly;

a front ring element 3 provided with a loading mouth 4 for frontallyloading the linen into the drum assembly 1; as stated, in a case of aside loading type of drum assembly, the ring element 3 will be replacedby a fully closed disc element (or provided with a mouth 4), whereas theband 2 will be provided with a linen loading door; and

a bottom or closing disc 5 for closing the drum assembly 1 from the rearthereof, supporting a cross assembly 6 in turn bearing the shaft 7 forrotatively driving said drum assembly (FIG. 2).

On the band 2 of the drum assembly 1 are moreover integrally providedtherewith entraining wedge elements 8. Said wedge elements, inparticular, are formed by respective projecting or deformed portions ofthe band 2, extending to the inside of the drum, and operating forallowing the drum to properly engage or grip the linen.

As is clearly shown in FIGS. 3 and 4, that section of each wedge element8 facing the ring 3 and provided for engaging with said ring element 3is formed, before assembling, with an edge portion 9 formed by aninwardly turned wall of the wedge element, and parallel to the surfaceof the front ring element 3 (or substantially perpendicular to the axisof said wedge element). In turn the mentioned surface of the ringelement 3 is provided, at each wedge element 8, with a window 10 clearlyshown in FIG. 5. Said window is substantially formed by a hole having acontour corresponding to that of the projecting edge portion 9 of therespective wedge-element 8. Moreover, the cut contour or edge of thewindow 10 is so deformed as to provide a deformed portion 11 facing theinside of the drum assembly 1, i.e. a direction substantiallyperpendicular to the mentioned edge portion 9.

The connection of the ring element 3 on the band 2, at the level of thewedge elements 8 and windows 10 is better shown in FIGS. 6 and 7. Fromsaid figures it should be apparent, in particular, that the ring element3 is applied on the band 2 by engaging the deformed portion 11 of thewindows 10 inside the respective wedge element 8, and arranging saiddeformed portion above said projecting edge portion 9 and transverselyof the latter, thereby substantially bridging it (FIG. 6). During thisoperating step, the connection is obtained, in a centered manner, bycausing the deformed portion 11 of the ring element 3 to abut againstthe contour of the edge portion 9 of the wedge element 8, which isarranged at substantially 90° with respect to said deformed portion.Said deformed portion 11, guided by the abutment on the edge portion 9,is shown in solid line in FIG. 7.

Starting from the mentioned self-centered arrangement of said deformedportions 11 arranged inside the respective wedge elements 8, the mutualconnection of the mentioned parts (and accordingly between the band 2and ring element 3) is performed by upsetting each individual deformedportion 11 against the projecting edge portion 9 of the respective wedgeelement 8 (FIGS. 8 and 9). This operation, which is performed as a coldupsetting operation, causes the deformed portions 11 of the ring element3 to be at first bent inwardly or rearwardly and then pressed againstthe projecting edge portion 9 of the respective wedge element 8. Thus, abroad sealing surface between the mentioned parts is obtained,corresponding to that of the deformed portion 11 bent above and pressedagainst the edge portion 9 of each wedge element 8 (which surface isclearly shown in FIG. 9).

According to a preferred embodiment thereof, the inventive method formaking the improved drum assembly, which has been above disclosed,comprises the steps of:

providing a cylindric band 2 including a plurality of wedge elements 8each having an edge portion 9 formed by an inwardly projecting wall ofthe wedge element, said wall being substantially transversely orientedof said wedge element, i.e. being perpendicular to the surface of saidband 2;

providing a ring element 3 (or a front cover element) including aplurality of windows 10 at each wedge element 8, said windows beingprovided with a deformed portion 11 perpendicular to the ring element 3;

connecting the ring element 3 on the cylindric band 2 by engaging thedeformed portions 11 inside the respective wedge elements 8, andarranging said deformed portions 11 above and substantially at 90° withrespect to the related edge portion 9; and

upsetting each deformed portion 11 against said edge portion 9, therebycausing said deformed portion to be rearwardly bent and pressed againstthe surface of said edge portion 9, thereby providing a gripping forcethereagainst.

According to the modified embodiment shown in FIGS. 10 and 11, the wedgeelements 8 are provided with a portion 12 outwardly axially projectingwith respect to the band 2, to be engaged within the windows 13 of thefront ring or cover element 3. In this modified embodiment, said windowsare substantially analogous to the above disclosed windows 10, with thedifference that they are free of any projecting deformed portions. Theconnection is in this case performed by upsetting the edge 12 of thewedge elements 8 inside the windows 13, by causing said edge to be atfirst rearwardly bent and then pressing it against the correspondingportion of the front ring or cover element 3 (FIG. 11).

The invention as disclosed and illustrated is susceptible to severalmodifications and variations which, however, will come within the scopeof the accompanying claims.

Thus, for example, the engagement projecting wall 9 for engaging thewedge element 8 and ring element 3 can be replaced by a simpleprojecting rib, to be properly gripped by the mentioned upsetting of thedeformed portion 11 of the ring element 3. Moreover, this can beobtained independently from the provision of the windows 10, saidwindows providing an essential function only with reference to themodified embodiment shown in FIGS. 10 and 11. Finally, the configurationor shape of the wedge elements 8 and windows on the front ring or coverelement can be any depending on the designing requirements of themachine.

What is claimed is:
 1. A method for making a drum assembly for washingand drying machines comprising the steps of: providing a cylindric bandincluding a plurality of wedge elements having and edge portion formedby a wall projecting toward an inside of a wedge element andsubstantially perpendicular to a surface of said band; providing a ringelement including a deformed portion projection from and perpendicularto said wall of said wedge elements; and urging said deformed portionagainst said wall, thereby pressing said deformed portion on said wallsuch that said deformed portion and said wall extend mutually parallelto form a broad sealing surface between said deformed portion pressed onsaid wall for forming a direct mechanical connection between said bandand said ring element.
 2. A method according to claim 1, characterizedin that said deformed portion is made by bending an inner edge portionof a corresponding window formed on a surface of said ring elementreceiving a connection with a respective wedge element.
 3. A method formaking a drum assembly for washing and drying machines comprising thesteps of: providing a cylindric band including a plurality of wedgeelements having an edge portion formed axially projecting toward anoutside of a wedge element; providing a ring element having windows atsaid edge portion of said wedge elements; and urging said projectingedge portion inside a corresponding window, thereby pressing saidprojecting edge portion against a contour of said corresponding window,thereby providing a direct mechanical connection between said band andsaid ring element.
 4. A method for making a drum assembly according toclaim 1, characterized in that said method comprises the step of coldclamping said ring element and said band, at said wedge elements of saidband.
 5. A method according to claim 4, characterized in that said coldclamping step comprises a press-deforming operation.
 6. A methodaccording to claim 4, characterized in that said cold clamping step ispreceded by a connecting step in which said ring element is connected tosaid band.
 7. A drum assembly for washing and drying machines, of thetype comprising a cylindric band provided with a plurality of wedgeelements facing an inside of said drum assembly, a rear closing disc anda front ring element, and connecting means for mechanically directlyconnecting said ring element and band, at said wedge elements of saidband, said connecting means comprising a pair of mutually pressed andmutually parallel like extending mating parts of respectively said ringelement and each of said wedge elements which together form a broadsealing surface between the mating and pressed parts.
 8. A drum assemblyaccording to claim 7, characterized in that said connecting meanscomprise projecting or raised portions each provided on an engagementsection of each said wedge element with said ring element, and adaptedto cooperate with corresponding projecting portions of said ringelement.
 9. A drum assembly according to claim 8, characterized in thatsaid projecting portions comprise a wall formed on an end of each saidwedge element facing said ring element and oriented toward the inside ofsaid wedge elements at a position substantially parallel to a surface ofthe ring element on which said wall must be connected.
 10. A drumassembly according to claim 9, characterized in that said projectingportions of said ring element comprise a deformed portion provided at aconnection section on each said wedge element and having such a size andshape suitable for engagement inside each said wedge element, above andbeyond said projecting wall.
 11. A drum assembly according to claim 10,characterized in that said deformed portion comprises a wall orientedtowards the inside of said drum assembly.
 12. A drum assembly accordingto claim 11, characterized in that said deformed portion, after havingperformed the mechanical connection, is turned rearwardly and urgedagainst said wall of the respective wedge element.
 13. A drum assemblyaccording to claim 12, characterized in that said deformed portion, isformed by a cut and upturned edge portion of a window formed throughthat portion of the surface of the ring element arranged at the level ofeach of said wedge elements.
 14. A drum assembly according to claim 7,characterized in that said connecting means comprise a portion of saidwedge elements axially projecting to an outside of said cylindric band,adapted to cooperate with corresponding window of said ring element, tobe locked on the contour of said window.
 15. A drum assembly accordingto claim 7, characterized in that instead of said ring element a closedcovering element is provided and that a loading mouth for laterallyintroducing linen to be washed in said drum assembly is formed on saidcylindric band.